PHP: How to get URL of relative file

问题

Does PHP have a native function that returns the full URL of a file you declare with a relative path? I need to get: "http://www.domain.com/projects/test/img/share.jpg" from "img/share.jpg" So far I've tried the following:

realpath('img/share.jpg');
// Returns "/home/user/www.domain.com/projects/test/img/share.jpg"

I also tried:

dirname(__FILE__)
// Returns "/home/user/www.domain.com/projects/test"

And this answer states that the following can be tampered with client-side:

"http://'.$_SERVER[HTTP_HOST].$_SERVER[REQUEST_URI].'img/share.jpg"

plus, my path will vary depending on whether I'm accessing from /test/index.php or just test/ without index.php and I don't want to hard-code whether it's http or https.

Does anybody have a solution for this? I'll be sending these files to another person who will upload to their server, so the folder structure will not match "/home/user/www.domain.com/"

回答1:

echo preg_replace(preg_quote($_SERVER['DOCUMENT_ROOT']), 'http://www.example.com/', realpath('img/share.jpg'), 1);

Docs: preg_replace and preg_quote.

The arguments of preg_replace:

preg_quote($_SERVER['DOCUMENT_ROOT']) - Takes the document root (e.g., /home/user/www.domain.com/) and makes it a regular expression for use with preg_replace.
'http://www.example.com/' - the string to replace the regex match with.
realpath('img/share.jpg') - the string for the file path including the document root.
1 - the number of times to replace regex matches.

回答2:

How about

echo preg_replace("'". preg_quote($_SERVER['DOCUMENT_ROOT']) ."'",'http://www.example.com/', realpath('img/share.jpg'), 1);

来源：https://stackoverflow.com/questions/27390829/php-how-to-get-url-of-relative-file

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php

url

relative-path